Effects of X-radiation on Growth and Function of the Repair Blastema (Granulation Tissue)

Summary

The Selye pouch technique has been used to stimulate growth of the repair blastema and angiogenesis and measure radiosensitivity of capillary blood vessels in the subcutis. Measurements of radiation damage to the tissue were based on (i) weight per unit area and corresponding DNA content of the repair blastema, (ii) the volume of blood produced in the pouch by angiogenesis and (iii) vascular macrocolony counts. Colony counts gave a D₀ value of ∼240 rads for single-dose and ∼180 rads recovery for split-dose irradiation. No significant difference was observed for single doses of irradiation given shortly before or after raising the pouches. Increasing the interval between irradiation of intact skin and raising of the pouch, was associated with rapid and marked repair of radiation damage; a delay of 2–3 weeks resulted in a dose-reduction factor of 500–625 rads for single doses of 1500–1800 rads given to intact skin. Local irradiation of an established pouch with a single large dose (2–4 krads) rapidly destroyed the inner layer of actively growing angioblastic tissue and caused arrest of haemorrhage; the outer layers of differentiated tissue showed less damage.